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Title: Studies on geotropism in the roots of Pisum sativum with particular reference to the effects of exposure to auxins and anti-auxins
Author: Brownbridge, Margaret E.
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1954
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Experiments were carried out to investigate the relationship between the auxin content of the upper and lower halves of horizontal, primary roots of Pisum sativum and their growth during geotropism. A special klinostat was constructed to rotate the roots subsequent to gravitational stimulation. Geotropic curvature and growth of the roots were recorded photographically and studied in detail. A method was evolved for the estimation of the possible auxin content of roots during the geotropic reaction. Treatment with various concentrations of 2,4-Dichloro-phenoxyacetic acid, a synthetic hormone, and B Indoleacetic acid, (assumed to be the natural auxin in pea roots), modified the degree of the geotropic reaction of roots, depending on the concentration applied, but it did not change the nature or course of the reaction in any way. Treatment with various concentrations of an anti-auxin, -(l-naphthylmethylsulphide)-propionic acid, resulted in increased growth of the roots but the amount of geotropic curvature was reduced.-(l-naphthylmethylsulphide)-propionic acid applied in combination with high concentrations of 2,4-Dichlorophenoxy-acetic acid or B Indoleacetic acid prevented the inhibition of root growth normally caused by these hormone concentrations and a fairly normal geotropic reaction took place in the treated roots. A consideration of the results of the research led to the conclusion that the Went Cholodny theory of simple redistribution of existing auxin within the root was inadequate to explain completely the geotropic growth reaction. [beta] Indoleacetic acid or some similar hormone appeared to play a vital part in geotropism, but whilst its presence, or absence, and concentration determined the degree of the reaction, some other unknown system in the root was thought to be responsible for geo-perception and the initiation of the reaction.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Plant Sciences